Learn
The lunar calendar, briefly
What the Chinese lunar date is, and why it changes every month.
Every almanac day carries a lunar date: "Lunar 10/3" means the third day of the tenth lunar month.
Months and years
Lunar months begin at the new moon. Some years add a leap month to stay aligned with the sun, which is why the lunar month number can repeat. The year is named by its pillars — the year of the Horse, for instance.
Where it appears
GoodOmen keeps the lunar date as a header detail and a line in the full almanac. It is a cultural trace, not a second calendar to plan by.